Hair conditioners are utilized globally to improve the texture and appearance of human hair. These formulations may confer specific benefits that are broadly defined as hair manageability. More specifically, hair manageability may be thought of as a combination of benefits such as reduction and/or removal of static charge, detangling, strengthening, split-end removal, shine improvement, thickening, fragrance delivery, moisturization, lubrication and other properties that generally result in the perception of repair of damaged hair and of enhanced beautification.
Compositions have been discovered that provide conditioning benefits simultaneously with cleansing and are known in the field as “two-in-one shampoos.” Although these have gained significant popularity, the predominant proportion of hair conditioning products are applied after shampooing, and may be designed to be rinsed off (“rinse-off”) or left on (“leave-on”) the hair. A conditioner that is used after shampooing in a separate step is called a conventional conditioner.
Conventional conditioner formulations are typically made in the form of oil-in-water (O/W) emulsions. Although the O/W emulsion is the preferred type, other product forms such as gels, creams, solutions, pastes, sprays, and mousses are also provided.
One property of conditioners that is preferred among consumers is for the viscosity of the product to be sufficiently high such that upon application, the product provides a feeling of creaminess and cushion between the hair and the hand. Another property that is preferred is that lubricity is provided by the conditioner, and during rinse-off, this lubricity is perceived as immediate improvement in the softness and smoothness of the hair. Yet another property that is preferred is that the hair surface be revitalized after the hair has dried out. This can be demonstrated by the ease with which combing or brushing is accomplished, and by visual characteristics such as shine. Yet another property that is preferred is that the hair maintains the shape and texture desired by the consumer just after drying, brushing and/or combing. Terms such as “frizziness” and “flyaway” are used in the field to describe loss of shape and/or texture. These terms have a negative connotation, and are generally associated with a lack of conditioning of the hair.
Cationic materials have been found to be particularly effective for controlling viscosity, providing lubrication during rinse off, reducing wet and dry combing force, improving shine, and improving the texture and the shape of the hair. Hair consists predominantly of keratin, and its surface is rich in negatively charged amino acids. Cationic materials will thus bind to the hair by electrostatic attraction, and will not be rinsed out completely. Particularly effective cationic materials are those in which the cationic site is on one end of the molecule, with the remainder of the molecule consisting of a long hydrophobic moiety. Cationic materials of this type can create a temporary new hair surface in which the topography is filled with organic material. The smoother hair surface reduces friction between the hair surface and hair styling implements such as combs and brushes, as well as the hand. Additionally, the smoother surface will tend to improve the ability of light to reflect off of the hair that results in improved shininess. Although certain cationic materials are known to provide such benefits, there is an ongoing need for materials that improve upon them.
A particularly useful class of cationic materials that may provide the aforementioned benefits are the amidoamines. Amidoamines are derived from the reaction of fatty acids with polyamines that contain at least one tertiary amine group. Stearamidopropyl dimethylamine (Lexamine® S-13, Inolex Chemical Company, Philadelphia, Pa., USA) is the reaction product of stearic acid (linear, C-18) with dimethylaminopropylamine. Behenamidopropyl dimethylamine (Lexamine® B-13, Inolex Chemical Company, Philadelphia, Pa., USA) is the reaction product of behenic acid (linear, C-22) with dimethylaminopropylamine. Stearamidoethyl diethylamine (Lexamine® 22, Inolex Chemical Company, Philadelphia, Pa., USA) is the reaction product of stearic acid (linear, C-18) with diethylaminoethylamine. Each of these products has been used successfully for many years alone or in combination with other types of conditioning ingredients in hair conditioning compositions.
Commercial forms of behenic acid are known which are derived from Menhaden (fish) oil. One such product was available from Witco under the name Hystrene® 9022. The applicants are unaware of the actual behenic content. Applicants are also aware of a product which has a behenic amidoamine content of about 60-65% and a stearic amidoamine content of about 20-25%, such that the maximum stearic/behenic ratio is about 0.417. To the best of applicants' knowledge all such products were derived from the reaction of dimethylaminopropylamine with fatty acids.
Representative patents directed to use of amidoamines in hair formulations include U.S. Pat. No. 4,954,335, which describes the usefulness of amidoamines in the formulation of clear hair conditioners. U.S. Pat. No. 6,365,142 also discloses the use of amidoamines in combination with other ingredients to form a hair conditioner. U.S. Pat. No. 6,979,439 discloses the use of amidoamines in anti-dandruff preparations. Although the prior art discloses the possible use of amidoamines in combination in hair care formulations, there have been no disclosures that suggest a particular advantage of any such combinations. Additionally, applicants are unaware of a particular theory that has been applied to account for or predict any a potential relationship between chemical structure and physical properties that would serve as a basis for one skilled in the art to predict the benefits or outcome of particular combinations of such compounds other than what would be expected in terms of general additive contributions of individual components.